Understanding PV Diagrams and Temperature Changes in Ideal Gases

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In summary, the conversation revolves around PV diagrams and the relationship between pressure and volume. The expert suggests drawing various curves for different constant temperatures and observing how a diagonal line intersects them to determine the correct answer. The original question asks about the temperature of the gas, with the choices being either decreasing then increasing or increasing then decreasing. After trying to use the Ideal gas Law formula, the user discovers that the temperature would decrease the entire way, making it an incorrect choice and prompting them to seek help on PF.
  • #1
get_physical
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PV diagrams.
a DIAGONAL straight line going down (negative slope) on a PV digram with P on y-axis and v on x-axis.

The temperature of the gas ______________.
Choices:
Decreases then increase
Increase then decrease


At first I chose remains constant... but it was wrong. I tried to plug it into the Ideal gas Law formula, and i get T to decrease the entire way. but that isn't a choice.
 
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  • #2
Welcome to PF!

Hi get_physical ! Welcome to PF! :smile:

Hint: what would be the shape of the pv curve if the temperature was constant?

draw several curves (on the same graph paper) for different constant temperatures …

how does the diagonal line cut those curves? :smile:
 
  • #3
thankyou tiny-tim!
 
  • #4
how do i mark this as solved?
 
  • #5
get_physical said:
how do i mark this as solved?

Hi get_physical! :smile:

(sorry I didn't reply earlier … I'm not getting email notification of replies at the moment … are you getting them?)

Normally, you click "Thread Tools" at the top … but it got de-activated in the latest upgrade … see https://www.physicsforums.com/showthread.php?t=240061&highlight=solved". :rolleyes:
 
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FAQ: Understanding PV Diagrams and Temperature Changes in Ideal Gases

What is a PV diagram?

A PV diagram, also known as a pressure-volume diagram, is a graphical representation of the relationship between the pressure and volume of a gas during a thermodynamic process.

How is a PV diagram plotted?

A PV diagram is typically plotted with pressure on the y-axis and volume on the x-axis. The shape of the curve on the graph can indicate the type of thermodynamic process occurring.

What information can be obtained from a PV diagram?

A PV diagram can provide information about the work done by the gas, the change in internal energy, and the heat transferred during a thermodynamic process.

How does the area under the curve on a PV diagram relate to work?

The area under the curve on a PV diagram represents the work done by the gas during a thermodynamic process. The larger the area, the more work is done.

What are some real-life applications of PV diagrams?

PV diagrams are commonly used in the study of thermodynamics and can be applied to various systems, such as engines, refrigerators, and heat pumps, to analyze their efficiency and performance.

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